1. Field of the Invention
The present invention relates generally to coaxial cable connectors and coaxial cable/connector assemblies, and particularly to coaxial cable connectors suitable for coaxial assemblies.
2. Technical Background
Coaxial cable connectors such as RCA, BNC and F-connectors are used to attach coaxial cable to another object such as an appliance or junction having a terminal adapted to engage the connector. F-connectors are often used in conjunction with a length of coaxial cable to create a jumper cable assembly to interconnect components of a cable television system. A jumper typically has one coaxial connector (connector termination) at each end of the length of cable. The coaxial cable typically includes a center conductor, or inner conductor, surrounded by a plurality of outer cable components, for example the inner conductor is surrounded by a dielectric, in turn surrounded by one or more outer conductive layers, or metallic layers, such as a conductive grounding foil and/or braid, wherein the outer conductive arrangement is itself surrounded by a protective outer jacket. The dielectric can be plastic, rubber, glass, or ceramic. Various types of coaxial cable have different outer protective layers or jackets. The F-connector is typically secured over the prepared end of the jacketed coaxial cable by use of a crimp tool or compression tool specifically designed to crimp or actuate the connector. Once secured to the coaxial cable, the connector is then capable of transferring signals by engaging the connector with a threaded connection or threaded port, such as found on typical CATV electronic devices like set top converters, television sets or DVD players.
Crimp style F-connectors are known wherein a crimp sleeve is included as part of the connector body. A crimping tool must be used to deform the crimp sleeve onto the cable to secure the connector to a cable. For example, a special radial crimping tool, having jaws that form a hexagon, can be used to radially crimp the crimp sleeve around the outer jacket of the coaxial cable to secure such a crimp style F-connector over the prepared end of the coaxial cable, such as described in U.S. Pat. No. 4,400,050 to Hayward. However, crimping braided outer conductors can present some difficulties. To prevent deformation of the outer cable components in relation to the center conductor, a support sleeve of one form or another may be used. Usually, the braid is captured in a layer between a tubular outer ferrule and the connector body, wherein the outer ferrule is crimped onto the crimp sleeve which in turn is radially compressed into engagement with the cable, but such crimps are not typically considered to be highly reliable, because, for example, there are typically large voids in the interface allowing for corrosive degradation of the contact surfaces, and/or the mechanical pull strength to the joint does not approach the strength of the wire. Additionally, such a crimp connection typically allows relative movement between all three components, which results in a very poor, noisy electrical connection.
Another known form of F-connector includes an annular compression sleeve used to secure the F-connector over the prepared end of the cable. Rather than crimping a crimp sleeve radially toward the jacket of the coaxial cable, these F-connectors employ an annular compression sleeve, typically plastic, that is initially attached to the F-connector, but which is detached therefrom prior to installation of the F-connector. The compression sleeve includes an inner bore for allowing such compression sleeve to be passed over the end of the coaxial cable prior to installation of the F-connector. The remainder of the F-connector itself is then inserted over the prepared end of the coaxial cable. Next, the compression sleeve is compressed axially along the longitudinal axis of the connector into the body of the connector, which simultaneously causes the jacket of the coaxial cable to be compressed between the compression sleeve and the tubular post of the connector as the compression sleeve moves radially inward. An example of such a compression sleeve F-connector is described in U.S. Pat. No. 4,834,675 to Samchisen. A number of commercial tool manufacturers provide compression tools for axially compressing the compression sleeve into such connectors.
Standardized cable preparation tooling and connector actuation tooling have lead to a de facto standard in cable preparation dimensions and connector envelope configurations. Additional requirements for both in-door and out-door use have resulted in connector designs that require a relatively large number of components. While standardized cable preparation tooling and connector actuation tooling has increased flexibility and interchangeability in field installations where an installer is concerned with making cable connection using one or a few connectors at a particular location, the implementation of these standardized connector and tooling systems for the manufacture of cable assemblies such as CATV jumper cables in large quantities tends to limit the efficiency of mass assembly of the jumpers, thereby causing unnecessary expense to be incurred in the manufacture of the assemblies.
FIGS. 1A-1C are partial cutaway views along the centerline of a coaxial cable illustrating typical known in-field cable preparation. FIG. 1A shows cable 100 comprising center conductor 101, dielectric 102 surrounding and in contact with the center conductor 101, outer conductor or shield 103 surrounding and in contact with dielectric 102, braid 104 surrounding and in contact with shield 103, and jacket 105 surrounding and in contact with braid 104. Basic preparation techniques are noted in steps 1 through 3. FIG. 1A shows cable 100 cut out to a desired length. FIG. 1B shows the result of removing outer cable components to expose center conductor 101 and braid 103. The standard exposed length of braid 106 is ¼″, and the standard exposed length of center conductor 107 is 5/16″. A multitude of industry standard tools are available to perform the necessary cuts to achieve the “standard” dimensions illustrated in FIG. 1B. FIG. 1C shows the result of un-weaving of braid 104 and folding back of braid 104 along jacket 105, which is typically performed manually and requires dexterity and time to accomplish properly.
FIG. 2 is a side cutaway view along the centerline of a known connector/cable combination. Connector 200 shown in FIG. 2 illustrates a relatively high number (six) of component parts required to meet the combined indoor and outdoor functional requirements placed on many F connectors. Additionally, FIG. 2 illustrates a difference in outer diameter between the outermost diameters of coupling nut 201 and body 204, which provides a relatively small exposed region E1 of the proximal side of coupling nut 201 in which to grasp the coupler 201 during installation. A limited difference in outer diameter E1 (and the resulting limited area of exposure) can be somewhat mitigated by increasing clearance space 207 defined by the rear end 208 of the coupler 201 and the outer surface of body 204, wherein space 207 can allow installer fingers a greater purchase area, but may not provide an entirely satisfactory solution, particularly if coupling nut 201 is plated with a relatively low coefficient of friction, or slippery, material, such as nickel. Clearance space 207 can be somewhat useful for pushing coupling nut 201 forward during installation, but more access to the back of coupling nut 201 but would be more advantageous. However, couplers are typically provided in standard sizes, and, for given standard coupler sizes, practical limits exist on reducing the outer diameter of the body of known connectors (for example because such connectors need to be able to receive the folded back braid of the cable and need to be able to clamp onto the cable, the outside diameter of the body needs to be large enough to structurally accommodate those features), so limitations exist on the flexibility of increasing the difference in outer diameter E1 in known connectors, used in conjunction with known cable preparation methods.